rdatetimedebuggingdst

Time difference from two POSIXct objects is not calculated correctly

I have two datetime objects of class POSIXct as follows:

> x = as.POSIXct('2013-03-31 01:39:42')
> y = as.POSIXct('2013-03-31 03:11:24')

The time difference of the two datetimes is calculated as 31.7 minutes (or 1902 seconds).

> y - x
Time difference of 31.7 mins

However, the time difference in this case is 91.7 minutes (or 5502 seconds). Can someone please explain to me this error?

Solution

  • Have you ever heard of daylight saving time?

    x
#[1] "2013-03-31 01:39:42 CET"
y
#[1] "2013-03-31 03:11:24 CEST"

    Look at the time zones.

    Compare with this:

    x = as.POSIXct('2013-03-31 01:39:42', tz="GMT")
y = as.POSIXct('2013-03-31 03:11:24', tz="GMT")
y-x
#Time difference of 1.528333 hours